1. Field
The field of the present invention relates to systems and methods for generating light, and more particularly to electrodeless plasma lamps.
2. Background
Electrodeless plasma lamps may be used to provide point-like, bright, white light sources. Because electrodes are not used, they may have longer useful lifetimes than other lamps. Some plasma lamps direct microwave energy into an air cavity, with the air cavity enclosing a bulb containing a mixture of substances that can ignite, form a plasma, and emit light. However, for many applications, light sources that are brighter, smaller, less expensive, more reliable, and have longer useful lifetimes are desired.
Some plasma lamps use a solid dielectric waveguide body. An amplifier may be used to provide power to the waveguide body at a frequency causing it to resonate. A positive-feedback loop may be used to maintain resonance during operation of the lamp. Feedback obviates the need for precise prediction and implementation of the resonant frequency, enabling manufacturing tolerances on the body to be relaxed. Moreover, feedback maintains coupling across resonant frequency changes associated with large temperature swings. Instead of requiring a precisely tuned microwave source at a predicted, preselected operating frequency, an amplifier with a feedback loop can be used to adjust to changing lamp conditions during operation.
What is desired are improved systems and methods for providing power to, and obtaining feedback from, a plasma lamp to maintain a resonant condition. What is also desired are systems and methods for stable operation of a plasma lamp using amplifiers that have unstable regions of operation.